Home / Archives / Vol. 12 No. 1 (2024) / Articles SPATIAL DISTRIBUTION OF MOLAR INCISOR HYPOMINERALIZATION (MIH) OPACITIES IN FIRST PERMANENT MOLARS

Aim: To evaluate the spatial distribution of MIH opacities in first permanent molars (FPM). Materials and methods: an analysis of intraoral photographs of FPM with demarcated MIH opacities was conducted. The presence of opacity was computed in a digital matrix, discriminating the anatomical regions of the FPM surfaces. The frequencies of distribution of the opacities were descriptively analyzed through 227 FPM digital images of 89 children built in GIMP and Python and by Spearman correlation (= 0,05). Results: the occlusal surface was the most affected one (94% to 100%). In the upper FPM, the palatine surface was the second most affected one (84%-91%). In the lower FPM, the vestibular surface was the second most affected one (85%-80%). A similar pattern of opacity distribution was observed in the contralateral teeth. On smooth surfaces, opacities were more frequent in the regions closer to the occlusal surface than to the cervical one. Conclusion: MIH opacities were mostly present on occlusal, vestibular, and lingual/palatine surfaces, respectively. There is a possibility that the occurrences are in accordance with the chronology of dental formation.

Mesialización del sector posterior por la ausencia del primer molar mediante el uso de microimplantes / Mesialization of the posterior sector due to the absence of the first molar through the use of micro-implants

Se presenta un caso clínico de paciente femenina de 16 años, la cual reportó haber perdido su primer molar superior izquierdo por caries dos años atrás. Es una paciente con maloclusión clase II esquelética, mesofacial, perfil recto, clase I molar derecho, ausencia del diente 26, clase I canina derecha y tendencia a clase II canina izquierda, con apiñamiento leve superior e inferior y línea media dental inferior desviada a la izquierda. Se trató mediante el uso de microimplante, con el objetivo de mesializar los dientes 27 y 28 así como mejorar el asentamiento de la clase canina izquierda. Se finalizó de manera exitosa la mesialización de los dientes posteriores superiores izquierdos, estableciendo una adecuada oclusión, eliminando el apiñamiento, logrando una buena guía anterior con líneas medias dentales coincidentes, proporcionando una sonrisa funcional y armoniosa. El propósito de este caso es demostrar que con las herramientas y mecánicas adecuadas además de una buena planificación, se puede lograr el control del anclaje en el movimiento de cierre posterior a falta de un molar ausente, y así lograr establecer una adecuada oclusión.

A clinical case of a 16-year-old female patient is presented, who reported having lost her upper left first molar due to caries two years ago is presented. She is a patient with class II skeletal, mesofacial malocclusion, straight profile, class I right molar, absence of tooth 26, class I right canine and tendency to class II left canine, with mild upper and lower crowding and lower dental midline deviated to the left. It was treated through the use of a microimplant, with the objective of mesializing teeth 27 and 28 as well as improving the settlement of the left canine class. The mesialization of the upper left posterior teeth was successfully completed, establishing adequate occlusion, eliminating crowding, achieving good anterior guidance with coincident dental midlines, providing a functional and harmonious smile. The purpose of this case is to demonstrate that with the appropriate tools and mechanics in addition to good planning, control of the anchorage in the posterior closing movement can be achieved in the absence of an absent molar, and thus achieve adequate occlusion.

Effects of furcation involvement on molar survival in periodontally treated patients / Efectos de la furcación sobre la supervivencia molar en pacientes sometidos a tratamiento periodontal

Objective: This study aims to analyze the survival time of molar tooth according to furcation involvement (FI) classification among periodontally treated patients under a supportive periodontal care program. Materials and Methods: A retrospective study was con-ducted among 77 periodontitis patients with 240 molars who had undergone periodontal therapy that were followed up with supportive periodontal therapy (SPT) for at least five years. Periodontitis patients' data were retrieved from the periodontic clinical record. The clinical parameters of all involved molars and treatment modality were recorded at baseline and SPT. Results: A total of 69 (28.8%) molars were extracted during active periodontal therapy, while 17 (7.1%) were lost during SPT. The 5-year survival rate of molars was 83.5% (95% confidence interval [CI], 76.9-88.4) for FI=0 (n=141), 81.0% (95% CI, 56.9-92.4) for FI=I (n=18), 50.0% (95% CI, 33.8-64.2) for FI=II (n=21), and 25.0% (95% CI, 6.9-48.8) for FI=III (n=4). Additionally, the 10-year survival rate for molars with FI = III was 12.5% (95% CI, 1.0-39.2), which was lower than that of molars with FI = 0 (77.1%; 95% CI, 69.7-83.0). Conclusions: The presence of a high degree of FI classifica-tion, especially Class III, is associated with a lower survival rate of molars among periodontally treated patients. Retention of molars is possible on a long-term basis through a maintenance program of periodontal therapy.

Objetivo: Este estudio tiene como objetivo analizar el tiempo de supervivencia de los molares según la clasificación de implicación de la furcación (IF) entre pacientes tratados periodontalmente bajo un programa de cuidado periodontal de apoyo. Materiales y Métodos: Se realizó un estudio retrospectivo entre 77 pacientes con periodontitis con 240 molares que habían sido sometidos a terapia periodontal y fueron seguidos con terapia periodontal de soporte (TPS) durante al menos cinco años. Los datos de los pacientes con periodontitis se recuperaron de la Historia Clínica de Periodoncia. Los parámetros clínicos de todos los molares involucrados y la modalidad de tratamiento se registraron al inicio y en el TPS. Resultado: Se extrajeron un total de 69 (28,8%) molares durante la terapia periodontal activa, mientras que 17 (7,1%) se perdieron durante la TPS. La tasa de supervivencia de los molares a 5 años fue del 83,5% (intervalo de confianza [IC] del 95%, 76,9-88,4) para FI=0 (n=141), del 81,0% (IC del 95%, 56,9-92,4) para FI=I ( n=18), 50,0% (IC 95%, 33,8-64,2) para FI=II (n=21) y 25,0% (IC 95%, 6,9-48,8) para FI=III (n=4). Además, la tasa de supervivencia a 10 años para los molares con FI = III fue del 12,5 % (IC del 95 %, 1,0-39,2), que fue inferior a la de los molares con FI = 0 (77,1 %; IC del 95 %, 69,7-83,0). Conclusión: La presencia de un alto grado de clasificación FI, especialmente Clase III, se asocia con una menor tasa de supervivencia de los molares entre los pacientes tratados periodontalmente. La retención de los molares es posible a largo plazo mediante un programa de mantenimiento de terapia periodontal.

Coronectomia como técnica alternativa à exodontia de terceiros molares impactados com risco de lesão ao nervo alveolar inferior / Coronectomy as an alternative technique to the extraction of impacted third molars with risk of injury to the inferior alveolar nerve

A coronectomia consiste no procedimento em que se faz a remoção da coroa do dente deixando a raiz in situ. Tal técnica é indicada para dentes posteriores impactados que apresentem proximidade com o canal mandibular representando assim um risco ao nervo mandibular caso seja feita uma exodontia. O seguinte trabalho tem como objetivo demonstrar os aspectos positivos relacionados ao emprego da técnica de coronectomia para dentes posteriores impactados. Foram realizadas buscas bibliográficas nas bases de dados PUBMED, MEDLINE e sciELO usando os descritores "coronectomia", "coronectomy", "terceiros molares impactados", "trigeminal", "nerve damage", respeitando critérios de relevância quanto ao tema foram selecionados 31 artigos. Sabe-se que pelo canal mandibular passa o nervo alveolar inferior e esse é responsável pela inervação sensitiva de estruturas anatômicas importantes, logo dentes impactados que tenham grande proximidade com o canal mandibular quando empregadas técnicas de exodontia correm o risco de lesionar o nervo podendo gerar perda da sensibilidade de forma passageira ou permanente, a indicação para realização da técnica precisa ser feita posteriormente à análise radiográfica e tomográfica da relação do dente com o canal mandibular. A técnica consiste na remoção da coroa do dente e o suficiente da raiz abaixo da crista vestibular e lingual do osso, para que esse possa desencadear um processo de cicatrização natural sobre as raízes retidas. Conclui-se que a coronectomia é um procedimento alternativo seguro e eficaz para casos específicos que se tem indicação e apresenta prognóstico favorável.

The coronectomy consists of the procedure in which the crown of the tooth is removed leaving the root in situ. This technique is indicated for impacted posterior teeth in close proximity to the mandibular canal representing a risk to the mandibular nerve if an extraction is performed. The following study has the porpouse to demonstrate the positive aspects related to the use of the coronectomy technique for impacted posterior teeth. Bibliographic searches were carried out in the databases PUBMED, MEDLINE, sciELO, using the DeCS "coronectomy", "odontectomy", "trigeminal", "nerve damage", respecting the criterion of relevance to the topic, 31 articles were selected. It is known that the inferior alveolar nerve passes through the mandibular canal and is responsible for the sensitive innervation of important anatomical structures, so impacted teeth that are very close to the mandibular canal when extraction techniques are used has the risk of injuring the nerve, which may lead to temporary or permanent loss of sensitivity, the indication for performing the technique needs to be made after the radiographic and tomographic analysis of the affinity between the tooth and the mandibular canal. The technique consists of removing the crown of the tooth and enough of the root below the buccal and lingual crest of the bone, so that it can trigger a natural healing process on the retained roots. It is concluded that coronectomy is a safe and effective alternative procedure for specific cases that are indicated and have a favorable prognosis.

Morphology of the Second Mesiobuccal Canal in the Maxillary Second Molar / Morfología del Segundo Canal Mesiovestibular en el Segundo Molar Maxilar

SUMMARY: Failure to locate a complete canal system affects the prognosis of root canal treatment. A missed root canal is one of the most common reasons for failed root canal treatment. The prevalence of the second mesiobuccal canal in the maxillary second molar is relatively high and has a variety of configurations. Therefore, knowledge of its morphology is required in clinical endodontics. This review presented the canal in terms of its prevalence, classification, anatomical features, and the method for locating the second mesiobuccal canal in the maxillary second molar. Root canal treatment requires knowledge of tooth morphology, appropriate access preparation, and a thorough examination of the tooth's interior. Thus, clinicians should carefully employ various methods for assessing the anatomy of the entire root canal system to prevent failure in locating the second mesiobuccal canal. This canal can be located by modifying the access cavity design and utilizing specific instruments to improve the second mesiobuccal canal system visualization.

La falta de localización de un sistema completo de canal afecta el pronóstico del tratamiento de éste. La omisión de un tratamiento de canal es uno de los motivos más frecuentes por las que el tratamiento de canal fracasa. La prevalencia del segundo canal mesiovestibular en el segundo molar superior es relativamente alta y tiene una variedad de configuraciones. Por tanto, el conocimiento de su morfología es necesario en endodoncia clínica. Esta revisión presentó el canal en términos de su prevalencia, clasificación, características anatómicas y el método para localizar el segundo canal mesiovestibular en el segundo molar superior. El tratamiento de canal requiere conocimiento de la morfología del diente, una preparación adecuada del acceso y un examen exhaustivo del interior del diente. Por lo tanto, los dentistas deben emplear cuidadosamente varios métodos para evaluar la anatomía de todo el sistema de canales radiculares para evitar fallas en la localización del segundo canal mesiovestibular. Este canal se puede localizar modificando el diseño de la cavidad de acceso y utilizando instrumentos específicos para mejorar la visualización del sistema del segundo canal mesiovestibular.

Root canal therapy of maxillary molars with atypical canals:A report of three cases / 北京大学学报(医学版)

Maxillary molar with three roots and 3 to 4 canals is a common occurrence.However,in addition to common root canal anatomy,there may be significant differences in the number,distribution,and morphological structure of root canals.The success of root canal treatment is dependent on ensuring that all the intricate details associated with it are meticulously followed.Failure to locate all canals could have a negative effect on the treatment as it may lead to initiation or continuation of periapical pathology.Missed canals were the main reason for patients reporting back for nonsurgical root canal retreatment.Moreover,the bacteria residing in such canals could also result in persistence of symptoms.Root canal anatomy is complex,and the recognition of anatomic variations could be a challenge for clinicians.This article presents three cases of endodontic management of maxillary molars with atypical canal morphology.In the three cases of this study,the patients underwent cone beam computed tomographic(CBCT)examination before root canal treatment.The CBCT images revealed that the maxillary molars in case 1 and case 2 had 5 canals.Case 1:2 mesiobuccal(MB,MB2),two distobuccal(DB and DB2),and one palatal canal.Case 2:2 mesiobuccal(MB,MB2),one distobuccal(DB),and two palatal canals(MP and DP).In case 3,CBCT scan slices showed that the maxillary first molar presented as a C-shaped root canal with a rare tooth anomaly of taurodontism.Although C-shaped root canals were most frequently seen in the mandibular second molar,they might also appear in maxillary molars.A literature search revealed only a few case reports of C-shaped root canal systems in maxillary molars.Case 3 described the fusion between mesiobuccal and palatal roots of the maxillary first molar,forming a C-shaped mesiopalatal root canal.The above cases suggest that endodontists should always be aware of aberrancies in root canal sys-tem apart from the knowledge of normal root canal anatomy.CBCT as a means of diagnosis can be helpful for identifying and managing these complex root canal systems.This case series also highlights the impor-tance of magnification and illumination.Through using an endodontic microscope,clinicians can identify root canals that are difficult to locate or overlooked with normal vision.A correct access opening is a most important step to locate and negotiate the orifices of root canals.The use of ultrasonic tips can refine the access cavity and allow controlled and delicate removal of calcifications and other interferences to the ca-nal orifices,thereby helping to locate the extra orifices.

Three-dimensional finite element analysis of distal proximal occlusal defect of short crown molar restored with endocrown / 中国组织工程研究

BACKGROUND:For teeth with normal dental crown height,pulp cavity retention crown restoration with different depths of the pulp cavity and different repair materials affects the stress and flexural strength of tooth tissue.For short crown molar defects,the research on pulp cavity repair mainly focuses on clinical observation and in vitro flexural strength experiments. OBJECTIVE:To establish a three-dimensional finite element model for short crown molar restored by the endocrown after root canal treatment to analyze the effects of different pulp cavity retention depths and different repair materials on the distribution and size of dentin equivalent stress. METHODS:Based on establishing the complete model of the short crown mandible first molar,a three-dimensional finite element model was established for repairing the distal adjacent defect of the short crown molar with different pulp cavity retention depths(h=2,3,4 mm)and different repair materials(zirconia,lithium disilicate).Under the oblique loading,the equivalent stress distribution was observed.The peak value of dentin equivalent stress and the mean value of equivalent stress near the bottom of the mesial pulp cavity wall were calculated. RESULTS AND CONCLUSION:(1)Equivalent stress concentration areas:The stress of complete short crown molar and restored models mainly concentrated in the mesial root mesial neck and mesial root lingual neck.The stress concentration area was found in the mesial pulp cavity wall corresponding to the bottom layer of restored models,and the stress concentration was obvious in the 4 mm retention depth group.(2)Under the same repair material,the peak value of dentin equivalent stress was the lowest at 3 mm for all models after repair.The average value of equivalent stress near the bottom of the mesial pulp cavity wall was lowest at 3 mm.(3)Under the same retention depth,there was no significant difference between the two materials in the dentin equivalent stress peak and the mean value near the bottom of the mesial pulp cavity.(4)The results showed that under the conditions of this experiment,the endocrown was used to repair the defect of the short crown molar and the retention depth was 3 mm,which was more beneficial to protect the remaining dental tissue.The selection of zirconia or lithium disilicate as the repair material had little effect on the dentin stress.

Effect of arch shapes and missing second premolars on anchorage during maxillary molar distalization with clear aligners / 中国组织工程研究

BACKGROUND:The reciprocal force generated by the molar distalization with clear aligners can lead to anchorage loss.The effect of arch shapes and missing second premolars on anchorage has not been reported. OBJECTIVE:To analyze the effect of arch shapes and missing second premolars on anchorage during molar distalization with clear aligners using the finite element method. METHODS:Cone-beam CT data from an adult male were acquired from the database to establish the maxilla-upper dentition-periodontium-rectangular attachment-clear aligner model.The distal movement amount designed on the bilateral second molars was set to 0.25 mm.First,there were two groups in the study:second premolar bilateral presence and absence groups.Then,four subgroups in each group were created:tapered arch,ovoid arch,square Class Ⅱ Division 1 arch,and Class Ⅱ Division 2 arch groups.The Ansys software was used to calculate the displacement of the anchorage tooth and the stress of the periodontal ligament. RESULTS AND CONCLUSION:Mesial tipping and extrusion of first molars and premolars,labial inclination and intrusion of anterior teeth occurred during the upper second molar distalization with clear aligners.When the bilateral second premolars were missing,the mesial displacement of first molars increased significantly while that of first premolars and anterior teeth decreased in all groups.The square Class Ⅱ Division 1 arch group showed the least anterior labial inclination,while the tapered arch group showed the most.There was no significant difference between the ovoid arch group and the tapered arch group.Moreover,the magnitude of tipping in the square Class Ⅱ Division 2 arch group was slightly higher than that in the Class Ⅱ Division 1 arch group.The stress of the periodontal ligament of the anchorage teeth was concentrated on the cervical and apical regions of the teeth.And the lowest stress level was detected in the square arch group.Compared with the other groups,the stress on the labial cervical area of the periodontal ligaments was also significantly relieved in the square arch group.To conclude,the square arch is more favorable in terms of anterior anchorage control and periodontal ligament stress distribution.Anterior labial inclination efficiency can be increased in cases of Class Ⅱ Division 2 by designing the anterior labial inclination in conjunction with molar distalization.If the second premolar is missing during molar distalization,it is not conducive to opening up the space in the area of the missing tooth.

Effect of molar distalization with clear aligners on occlusal vertical dimension in different vertical craniofacial patterns / 中国组织工程研究

BACKGROUND:Previous studies have shown that clear aligners can achieve molar distalization effectively,but it is not yet clear how the vertical dimensions change in patients with different vertical craniofacial patterns after molar distalization. OBJECTIVE:To evaluate the effect of molar distalization with clear aligners on occlusal vertical dimension in different vertical craniofacial patterns. METHODS:Forty patients(13 cases of Class Ⅰ malocclusion,20 cases of Class Ⅱ malocclusion,and 7 cases of Class Ⅲ malocclusion)were selected,including 13 cases in the high angle group,17 cases in the average angle group,and 10 cases in the low angle group.Among them,the age ranged from 10 to 53 years,with an average of 28.5 years.All patients were subjected to clear aligners for molar distalization.Lateral cephalometric films were taken before and after treatment.Cephalometric measurements,including the sagittal and vertical indicators of teeth and jaws,were measured by the same orthodontist,and each indicator was measured 3 times and averaged. RESULTS AND CONCLUSION:After orthodontic treatment,the crowded dentition was corrected,the overbite and overjet were back to normal and the lateral profile was improved significantly in all 40 patients.The GoGn-SN in the high angle group decreased by 0.4°,while the GoGn-SN in the average and low angle groups increased by less than 1°,the ANS-Me in the three groups increased by less than 1 mm.There was no statistically significant difference before and after treatment.There was a statistically significant decrease in the U6-PP in the low angle group by 0.47 mm(P<0.01).The L1-MP and the U1-SN in the average angle group significantly decreased by 0.83 mm(P<0.05)and by 6.46°(P<0.001),respectively.In conclusion,molar distalization with clear aligner treatment can control the vertical dimension effectively,prevent clockwise mandibular rotation,and maintain the lower face height.Patients with high angle can also undergo invisible orthodontics to distal molars.The realization rate of the anterior tooth intrusion movement by using clear aligners is insufficient,and the intrusion design should be increased to prevent the elongation phenomenon in anterior teeth.

Three-dimensional finite element study on the effect of posterior tooth forward movement on temporomandibular joint stress in orthodontic reduction patients / 中国组织工程研究

BACKGROUND:Temporomandibular joint disorders are closely related to high stress in temporomandibular joint.With the change of molar position after tooth reduction extraction,the establishment of new occlusal relationship often leads to the change of internal stress environment of the temporomandibular joint. OBJECTIVE:To analyze the stress distribution of temporomandibular joint in patients undergoing orthodontic reduction tooth extraction with different degrees of molar forward movement using the three-dimensional finite element model of the maxillary complex and temporomandibular joint. METHODS:A case of individual normal occlusal patient was selected from the Orthodontics Department of Qingdao Municipal Hospital,Shandong Province,and the finite element models of 1/3 anterior molar space(extraction of four second premolar teeth)before and after reduction and 2/3 anterior molar space(extraction of 4 second premolar teeth)after reduction were established based on the cone-beam CT and MRI data.ABAQUS software was used to analyze the stress distribution of various parts of the temporomandibular joint during the interposition of tooth tips. RESULTS AND CONCLUSION:The stress distribution of the condyle,articular disc,and osteoarticular fossa in the model before and after the reduction was basically the same.The stress of the condyle was mainly distributed in the anterior and apical part of the condyle,the stress of the articular disc was mainly distributed in the middle band and lateral part of the articular disc,and the stress of the articular fossa was mainly concentrated in the anterior and apical part of the articular fossa.However,the equivalent stress value of the condyle,articular disc and articular fossa decreased after reduction.After orthodontic reduction extraction,the equivalent stress values of condyle and articular disc in the 1/3 anterior molar space model were smaller than those in the 2/3 anterior molar space model.From the perspective of biomechanics,orthodontic reduction extraction can reduce the stress of the temporomandibular joint and provide a good biomechanical environment.

Fracture resistance and marginal adaptation of primary molar defects repaired with ultra-high-molecular-weight polyethylene combined with various restorative materials / 口腔疾病防治

Objective@#To evaluate the impact of ultra-high-molecular-weight polyethylene (UHMWPE)-Ribbond fibers, when combined with different restorative materials, on fracture resistance and marginal adaptation of isolated primary molar defects, to provide a reference for clinical practice.@*Methods@#This study was approved by the Ethics Review Committee. A total of 72 extracted primary molars with complete crowns were collected, and 66 primary molars were randomly assigned as experimental groups for the fracture resistance and microleakage tests. The molars were divided into six groups (n = 11) based on the type of restorative materials and the application of Ribbond fibers: Group A1, 3M Filtek Z250 + Ribbond; Group A2, 3M Filtek Z250; Group B1, Beautifil II LS + Ribbond; Group B2, Beautifil II LS; Group C1, 3M Filtek Bulk Fill + Ribbond; and Group C2, 3M Filtek Bulk Fill. Groups A1, B1 and C1 received the fiber-reinforcing technique, whereas Groups A2, B2 and C2 received the direct restorative technique; the remainings were in Group D (blank control group), which did not receive treatment for the fracture resistance test. The fracture resistance test was divided into six experimental groups and one blank control group (n = 6). Primary molar teeth in each experimental group were prepared with Class II cavities and filled. The fracture load of all samples was detected, and the fracture mode was analyzed after thermal cycling. The microleakage test was divided into six experimental groups, with five in each group. Class I cavities with a diameter of 3 mm and depth of 2.5 mm were prepared within the mesial and distal marginal ridges on the occlusal surface and filled for primary molars in each group. Marginal microleakage was assessed after thermal cycling.@*Results@#The fracture resistance test results showed that the fracture resistance in groups that received the fiber-reinforcing technique was greater than that in groups that received the direct restorative technique: Group A1>Group A2, Group B1>Group B2, Group C1>Group C2 (P<0.05). The application of Ribbond fibers increased fracture resistance to all tested restorative materials by 37.08% to 39.34%. The proportion of tooth frac-ture decreased significantly in groups A1, C1 compared with A2, C2, with a significant increase in the occurrence rate of “Repairable” (P<0.05). The fracture resistance in Group A1 was significantly greater than that in Group B1 and Group C1 (P<0.05). The marginal microleakage test results showed that the microleakage depth in groups that received the fiber-reinforcing technique was smaller than that in groups that received the direct restorative technique: Group A1<Group A2, Group B1<Group B2, Group C1<Group C2 (P<0.05). The microleakage depth in groups that received the fiber-reinforcing technique decreased by 53.90% to 66.96% compared to that in groups that received the direct restorative technique. The microleakage depth in Group B1 was significantly less than that in Group A1 and Group C1.@*Conclusion@#The application of Ribbond fibers combined with various restorative materials could enhance fracture resistance and diminish the microleakage depth to improve marginal adaptation.

Clinical effect of Piezocision combined with a microporous technique on periodontal tissue reconstruction during anterior displacement of mandibular molars in adults / 中国基层医药

Objective:To investigate the clinical effectiveness of Piezocision combined with a microporous technique in accelerating periodontal tissue reconstruction during the anterior migration of mandibular molars in adults.Methods:A prospective, randomized, controlled study was conducted on 30 adult orthodontic patients recruited from Shaoxing Hospital of Traditional Chinese Medicine between January 2020 and September 2022. The inclusion criteria were patients who were unable to retain their first molars due to severe caries or long-term absence and were not suitable for implantation. Using the random number table method, the patients were randomly assigned to two groups: a simple orthodontic control group (Group A, n = 15) and a group that received Piezocision combined with a microporous technique (Group B, n = 15). After treatment, a comparison was made between the two groups in terms of mesial movement distance of the mandibular second molar, plaque index, gingival index, periodontal pocket depth, width of keratinized gingiva, gingival recession, clinical attachment loss, mesial root resorption of the mandibular second molar, alveolar bone height (measured as the distance from the center of the lower incisor to the anterior margin of the chin, referred to as the LM-AC distance), mandibular bone height (measured by the distance from the distal or mesial surface of the root to the alveolar bone margin, denoted as the CEJ-AC distance), and orthodontic satisfaction. Results:The mesial movement distances of the mandibular second molar in Group A patients were (0.86 ± 0.13) mm, (2.75 ± 0.24) mm, (3.54 ± 0.24) mm, and (4.67 ± 0.13) mm at 4, 6, 8, and 12 weeks, respectively. These values were significantly greater than those observed in Group B, which were (0.43 ± 0.06) mm, (1.27 ± 0.14) mm, (1.85 ± 0.53) mm, and (2.65 ± 0.06) mm ( t = 6.83, 14.13, 18.24, 23.78, all P < 0.001). Prior to treatment, there were no statistically significant differences in plaque index, gingival index, periodontal pocket depth, width of keratinized gingiva, gingival recession, or clinical attachment loss between the two groups (all P > 0.05). After treatment, Group A did not exhibit statistically significant differences in plaque index, gingival index, width of keratinized gingiva, and gingival recession compared with baseline values (all P > 0.05). However, in Group A, periodontal pocket depth and clinical attachment loss significantly increased compared with pretreatment levels ( t = -2.57, -7.50, both P < 0.05). After treatment, Group B exhibited significantly increased values for periodontal pocket depth, width of keratinized gingiva, gingival recession, and clinical attachment loss compared with baseline levels ( t = -8.66, -5.57, -45.33, -9.72, all P < 0.001). Furthermore, these values were significantly higher in Group B compared with those in Group A ( t = -4.28, -3.18, 10.00, 10.69, all P < 0.001). A statistically significant difference was also observed between the two groups in terms of mesial root resorption of the mandibular second molar ( t = 4.14, P < 0.001). However, there was no statistically significant difference in LM-AC distance between the two groups after treatment ( P > 0.05). Conclusion:The combination of Piezocision and a microporous technique can effectively accelerate the anterior migration of mandibular molars in adults while maintaining the health of periodontal tissues. This approach holds great potential for clinical promotion.

The Prevalence, Severity and Pattern of First Permanent Molars’ Dental Caries in Children Attending A Postgraduate Dental Hospital: A Retrospective Study

@#Introduction: First permanent molars (FPMs) erupt early and their anatomy and location leave them susceptible to dental caries. This study aimed to retrospectively determine the prevalence, severity and pattern of dental caries of FPMs and investigate their relationship if any with demographics and medical health status of the partcipants. Methods: This was a retrospective cross-sectional study. A sample of the digital case notes and radiographs of children aged 5 to 12 years who attended the only postgraduate dental hospital in Dubai were accessed. The recorded data included the children’s demographic variables and the carious status of each FPM as recorded in the notes on the initial assessment. Descriptive and statistical analyses were conducted (P<0.05). Results: A total of 2984 FPMs were obtained from the digital records of 774 children. Their mean age was 8.07 (±2.23) years and only those that met the inclusion criteria were included in the study. The prevalence of dental caries and mean Decayed Missing Filled Surfaces of FPMs, were 42% and 0.3 (±0.04), respectively. The most prevalent decayed surface was the occlusal (29.2%), followed by mesial, buccal, palatal/ lingual, distal surfaces (24.2 %; 6.6 %; 3.1 %; 2.3 %) respectively. Children with medical problems and/or special needs had a significantly higher level of caries in the buccal surfaces (12.3%) (P=0.042). Conclusion: Caries of FPMs in a sample of Dubai children studied was prevalent, especially in those with special healthcare needs, thus indicating a necessity for targeted prevention and treatment focused on these keystone teeth.

Meta-analysis of the efficacy of invisible orthodontic appliances for maxillary molar distalization in adult patients / 口腔疾病防治

Objective@#To evaluate the clinical efficacy of invisible orthodontic appliances without brackets for the distal movement of maxillary molars to improve the ability of orthodontists to predict treatment outcomes.@*Methods@#Web of Science, Cochrane Library, Embase, PubMed, Wanfang Database, CNKI Database, and VIP Database were searched for studies investigating the efficacy of invisible orthodontic appliances for distal movement of maxillary molars in adult patients and published from database inception to August 1, 2023. A total of three researchers screened the studies and evaluated their quality and conducted a meta-analysis of those that met quality standards.@*Results@#This study included 13 pre- and postcontrol trials with a total sample size of 281 patients. The meta-analysis revealed no significant differences in the sagittal or vertical parameters of the jawbone after treatment when compared with those before treatment (P>0.05). The displacement of the first molar was MD=-2.34, 95% CI (-2.83, -1.85); the displacement was MD=-0.95, 95% CI (-1.34, -0.56); and the inclination was MD=-2.51, 95% CI (-3.56, -1.46). There was a statistically significant difference in the change in sagittal, vertical, and axial tilt of the first molar before and after treatment. After treatment, the average adduction distance of the incisors was MD=-0.82, 95% CI (-1.54, -0.09), and the decrease in lip inclination was MD=-1.61, 95% CI (-2.86, -0.36); these values were significantly different from those before treatment (P<0.05).@*Conclusion@#Invisible orthodontic appliances can effectively move the upper molars in a distal direction and control the vertical position of the molars. When the molars move further away, there is some degree of compression and distal tilt movement, which is beneficial for patients with high angles. The sagittal movement of incisors is beneficial for improving the patient's profile.

Risk factors associated with occlusal caries in first permanent molars in a school program: longitudinal study

Aim: Evaluate the longitudinal status of dental caries in the occlusal surface of first permanent molars (FPM) and to identify risk factors for the progression to cavitated caries lesions in a school oral health program. Methods: Children who were enrolled in the program between September 2017 and October 2019, 5 to 10 years-old, presenting the four FPM were included. Four calibrated examiners assessed dental caries according to Nyvad criteria. Descriptive analysis included frequency, mean, and standard deviation calculations. Chi-square test was used in the bivariate analysis and, logistic regression adjusted for cluster effect was used to identify significant risk factors for cavity among the following independent variables: gender, age in the baseline, deft, upper/lower molar, initial caries score, Molar Incisor Hypomineralization (MIH), fluorosis, occlusal sealing. Odds ratio (OR) and respective confidence intervals (CI) are presented. Results: From 174 children enrolled in the program between 2017/2019, 120 were reevaluated in 2022. Eleven (2.6%) FPM in 11 children (9.2%) presented cavitated caries in the follow up examination. Significant risk factors for cavity were caries experience in the primary teeth (OR = 5.59; CI: 1.4 ­ 22.3) and the presence of MIH (OR = 5.33; CI: 1.6 ­ 18.1). Most of the active lesions in the follow up were considered active in the baseline examination. Conclusions: The progression to cavity was relatively low, significantly influenced by past caries experience and MIH

Using manual versus mechanized glide path instruments and ProTaper Gold versus ProTaper Next systems in curved canals: micro-CT study

Abstract The aim of this study was to evaluate the root canal shaping effect of ProTaper Gold (PTG) versus ProTaper Next (PTN) instrumentation systems, and of a manual #15 K-type file (K15) versus the ProGlider (PG) mechanized instrument for glide path creation, in severely curved mesial canals. Twenty-four mandibular molars with two separate mesial canals were anatomically matched using computed tomographic scanning, and then divided into two groups (n=12) according to the glide path instrument used, either K15 or PG. In all teeth, the PTG system was used to prepare the mesiobuccal canal, and the PTN, the mesiolingual canal. The teeth were scanned by computed microtomography, before and after root canal preparation, and the values of the initial volume, final volume, volumetric variation, untouched walls, and canal transportation variables were determined. The data were analyzed using the two-way ANOVA test, and the Tukey test for multiple comparisons. There was no significant difference among the study groups regarding volumetric variation or root canal transportation, either in the cervical, middle or apical thirds, or in the entire root canal (p>0.05). In the apical third, the percentage of untouched walls was significantly higher in groups using K15 than in those using PG (p<0.05), namely 33.144% and 23.285%, respectively, irrespective of the instrumentation system. In the other regions, there was no difference between K15 and PG regarding this variable. It was concluded that PG was associated with a lower rate of untouched walls in the apical region than K15.

The incidence of unfilled second mesiobuccal canals and periapical lesions in maxillary molars by cone-beam computed tomography E-VOL DX software

This study evaluated the incidence of unfilled second mesiobuccal (MB2) canals and periapical lesions in first maxillary molars using CBCT e-Vol DX software. Hence, 326 CBCT images of first maxillary molars of patients undergoing endodontic treatment were selected. The e-Vol DX software performed a retrospective review of these images, recording the presence or absence of MB2 canals, filling, and periapical lesions in first maxillary molars. Specific statistical analysis was performed at a 5% significance level. Unfilled MB2 canals were highly frequent in first maxillary molars and significantly associated with periapical lesions in the mesiobuccal root of these teeth (p<0.05). The CBCT e-Vol DX software effectively detected MB2 canals, and unfilled canals may be associated with periapical lesions.

Extracción terapéutica de primeros molares Permanentes severamente destruidos en dentición mixta

En dentición mixta, el 1°Molar permanente es el más susceptible a caries, que desencadena un ciclo restaurador repetitivo y pérdida. El objetivo de este estudio fue evaluar factores determinantes de la extracción terapéutica de 1°Molares permanentes severamente destruidos en dentición mixta antes de la erupción del segundo molar permanente con un favorable cierre espontáneo del espacio residual. La metodología consistió en una revisión sistemática exploratoria en PubMed mediante búsqueda estratégica/específica. Incluyó diez artículos que abordaron factores como la edad cronológica ideal, etapa de desarrollo del segundo premolar y molar permanente, presencia del tercer molar, cierre espontáneo residual, pronóstico, y necesidad de tratamiento ortodóncico. En conclusión, la extracción terapéutica del 1°Molar antes de la erupción del segundo molar permanente está asociada con un favorable cierre espontáneo del espacio residual. Se evidencia mayor éxito con la presencia del tercer molar, segundo molar en etapa E y segundo premolar en etapa F (Demirjian).

Abstrato: Em dentição mista, o 1°molar permanente é o mais suscetível a cáries, desencadeando um ciclo restaurador repetitivo e perda. O objetivo deste estudo foi avaliar fatores determinantes da extração terapêutica de 1°molares permanentes severamente destruídos na dentição mista antes da erupção do segundo molar permanente com uma região espontânea favorável do espaço residual. A metodología utilizada no PubMed consistiu em uma revisão exploratória por meio de busca estratégica/específica. Foram incluídos dez artigos, abordando fatores como a idade cronológica ideal, estágio de desenvolvimento do segundo pré-molar e molar permanente, presença do terceiro molar, cierre espontâneo residual, pronóstico e necessidade de tratamento ortodôntico. Em conclusão, a extração terapêutica do 1°molar permanente antes da erupção do segundo molar permanente está associada a um fechamento espontâneo favorável do espaço residual. Maior sucesso está descrito quando na presença de terceiro molar, segundo molar no estágio E e segundo pré-molar no estágio F (Demirjian).

During mixed dentition, the 1st permanent molar is the most susceptible to caries, triggering a repetitive restorative cycle and loss. This study aimed to evaluate determinants of therapeutic extraction of severely damaged 1st permanent molars in mixed dentition before the eruption of the second permanent molar with favorable spontaneous closure of the residual space. The methodology involved a scoping review on PubMed using a specific search strategy. Ten articles were included addressing factors such as the ideal chronological age, stage of development of the second premolar and permanent molar, presence of the third molar, residual spontaneous closure, prognosis, and need for orthodontic treatment. In conclusion, therapeutic extraction of the 1st molar before the eruption of the second molar is associated with favorable spontaneous closure of the residual space. Greater success is evident with the presence of the third molar, the second molar in stage E, and the second premolar in stage F (Demirjian).

Natural canal deviation and dentin thickness of mesial root canals of mandibular first molars assessed by microcomputed tomography

Abstract The aim of this study was to assess the centralization and dentin thickness of mesial root canals of the first mandibular molars by microcomputed tomography (micro-CT). Material and methods: Ninety-nine mandibular molars of Vertucci's type IV canals were scanned by micro-CT. The mesiodistal deviation and centroid were assessed, in both mesiobuccal (MB) and mesiolingual (ML) canals, for the apical 4mm and the full canal length. Results: The dentin thickness was similar for both MB and ML canals. The narrowest thickness was in the distal wall of an MB canal (0.07mm), while the widest was found in the mesial wall of an MB canal (2.46mm). In centroid analysis, both the MB and ML canals exhibited deviations when compared to the root centroid, along the full canal length and the apical 4mm. For the MB canal, the mean deviation was 0.83mm (0.02 mm-2.30 mm) for the full canal and 0.18mm (0.01 mm-1.01 mm) for apical 4mm. Similarly, for the ML canal, the mean deviation measured 0.83 mm (0.05mm-3.99mm) for the full canal and 0.21 mm (0.01mm-1.01mm) for the apical 4 mm. Overall, deviations were observed towards the mesial of the roots, with 69% for MB and 57% for ML canals for the full canal, and 51% for MB canals within the 4 mm. The exception was the ML canal, which exhibited a higher deviation towards distal in the apical 4mm, accounting for 52% of cases. The dentin thickness was consistent between the mesial canals of mandibular molars. However, there is no centrality of mesial canals in their roots, with frequent deviation to mesial.

Resumo O objetivo deste trabalho foi avaliar a centralização e a espessura da dentina dos canais radiculares mesiais de primeiros molares inferiores por meio de microtomografia computadorizada (micro-CT). Material e métodos: Noventa e nove molares inferiores com canais tipo IV de Vertucci foram escaneados por micro-TC. O desvio mesiodistal e o centroide foram avaliados para os canais mesiovestibular (MB) e mesiolingual (ML), nos 4mm apicais e em todo o comprimento do canal. Resultados: A espessura da dentina foi semelhante para os canais MB e ML. A espessura mais estreita foi encontrada na parede distal de um canal MB (0,07mm), enquanto a mais larga foi encontrada na parede mesial de um canal MB (2,46mm). Na análise centroide, tanto o canal MB quanto o ML exibiram desvios quando comparados ao centroide da raiz, ao longo de todo o comprimento do canal e nos 4 mm apicais. Para o canal MB, o desvio médio foi de 0,83mm (0,02mm-2,30mm) para canal inteiro e 0,18mm (0,01mm-1,01mm) para o apical de 4mm. Da mesma forma, para o canal ML, o desvio médio mediu 0,83 mm (0,05 mm-3,99 mm) para o canal inteiro e 0,21 mm (0,01 mm-1,01 mm) para os 4 mm apicais. No geral, foram observados desvios em direção mesial das raízes, sendo 69% para canais MB e 57% para canais ML para canal inteiro, e 51% para canais MB dentro dos 4 mm. A exceção foi o canal ML, que apresentou maior desvio para distal nos 4mm apicais, representando 52% dos casos. A espessura da dentina foi consistente entre os canais mesiais dos molares inferiores. Entretanto, não há centralidade dos canais mesiais em suas raízes, com frequente desvio para mesial.

Effect of music therapy on pain and anxiety during third molar surgery

Music therapy has been used with promising results to reduce pain and anxiety in surgical specialties. It is suggested to reduce anxiety and pain perception during dental surgeries and thereby improving clinical outcomes. Aim: The aim of this study is to determine whether listening to music during trans-alveolar mandibular third molar extraction reduces pain perception and anxiety. Methods: One hundred and forty-six adult participants were randomized into music and non-music groups, with each group comprising seventy-three participants. Each participant had trans-alveolar third molar extraction with or without music intervention depending on the group randomly assigned. Pain scores of participants were measured at one minute after consent, during and after administration of local anaesthetic, during osteotomy, after tooth delivery, and one minute after flap closure. Postoperative pain scores were recorded at one-hour, 3-hour, 6-hour, 24-hour and 48-hour after the last stitch. Pre- and post-operative anxiety scores were also recorded. Descriptive statistics was used to describe sociodemographic data. Student t-test was used to compare the mean of quantitative variables between the groups while chi-square test was used to compare proportions and to investigate association between categorical variables. The statistical significance was defined at p<0.05. Results: The study showed similar sociodemographic characteristics, baseline clinical features and duration of surgery between groups. Pain score peaked during local anaesthetic administration (p = 0.254) and at 3 hours after surgery (p = 0.170) but no statistically significant difference was observed in the mean pain score. The mean anxiety scores also revealed no statistically significant differences. Conclusion: Music was found to add no significant anxiolytic and adjunctive analgesic benefit to participants who underwent third molar surgeries in this study